The present invention relates generally to surgical instruments and, more particularly, to a skin biopsy punch having a crescent shaped cutting member. As is well-known in the art, abnormalities found on the surface of the skin, such as tumors or lesions, are removed by a simple surgical procedure for further examination and analysis. Traditionally, this surgical procedure was performed "free-hand" by a surgeon using a scalpel. An incision was made around the skin abnormality to create an isolated piece of skin that was lifted by forceps to expose the underlying tissue. The tissue would then be cut away by a scalpel or scissors such that the abnormality could be removed. Typically, an elliptical incision was made about the skin abnormality so that the wound would heal with the least amount of visible scarring. The elliptical incision also accelerated the healing process because the exposed surfaces of the wound could be evenly joined together with a minimum stretching of the skin.
While such a surgical procedure was relatively simple, it was difficult for the surgeon to make precise elliptical incisions around the skin abnormality such that the healing benefits provided by an elliptical incision were not always realized. In an attempt to obviate this problem, surgical incision guides were devised. One such example of a guide is shown in U.S. Pat. No. 4,192,312 issued to Wilson. Wilson shows a patch of material which acts as a template and is placed over the skin abnormality so as to guide the scalpel while the surgeon made the free-hand incision. While such a device lessened the problems associated with free-hand incisions, making precise cuts was still dependent on the skill of the individual surgeon. Moreover, the incision guides did nothing to insure that the scalpel cut at a uniform depth such that removed tissue had a uniform thickness. Obtaining tissue specimen of uniform thickness is critical for the performance of pathological analysis and diagnosis.
One such skin biopsy punch, also referred to as a circular punch, contained an incision blade which was circular in shape. Such circular punches, when used to remove skin lesions, created an oval-like defect after use. If the oval-like defect was sufficiently small, the wound would be allowed to heal. However, larger incisions would require closure which would result in "dog ears" on each of the oval ends of the defect. The surgeon would be required to notch the oval ends of the defect, creating a linear defect which could then be closed by suture or staple. A circular skin biopsy punch is shown in U.S. Pat. No. 3,515,128 issued to McEvoy.
In U.S. Pat. No. 3,990,451, issued to Gibbs, a surgical instrument for removing skin lesions having a navicular shape was developed. However, the incision blade of Gibbs is difficult to manufacture because it has a complex convex cutting edge. Moreover, the Gibbs device is difficult to use because the surgeon must rock the convex cutting head across the surface of the skin to make the incision. The shape of the cutting head and the rocking cutting action also make it difficult to remove a specimen having a uniform thickness as the specimen will be thicker at its middle than at its ends. Thus, a biopsy punch that has a simpler and less expensive construction and is simpler to use than the Gibbs device is desired.